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Click on these links for a "hot lap" of the TZ350 and 250 Website:                                     

TZ Performance information:

Click on the links below to read some interesting articles:

 

 

Picture: Ron Haslam chases John Newbold circa: 1974.

 

TZ 250

    final drive   13x36 13x35 13x34 13x33 15x36 15x35 15x34 16x36  15x33 16x35 16x34  17x36 16x33  17x35 17x34 17x33
  gearbox                                    
1st 29 15 1.93 42.1% 73 76 78 80 85 87 90 90 92 93 96 96 99 99 102 105
2nd 27 19 1.42 57.3% 100 103 106 109 115 119 122 123 126 127 130 131 134 134 138 143
3rd 27 24 1.13 72.4% 126 130 134 138 146 150 154 155 159 160 165 165 169 170 175 180
4th 25 26 0.96 84.7% 148 152 156 161 170 175 180 182 186 187 192 193 198 199 205 211
5th 20 23 0.87 93.7% 163 168 173 178 188 194 200 201 206 207 213 214 219 220 226 233
6th 22 27 0.81 100% 174 179 185 190 201 207 213 215 219 221 227 228 234 234 241 249

 

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 TZ 350

    final drive   13x36 13x35 13x34 13x33 15x36 15x35 15x34 16x36  15x33 16x35 16x34  17x36 16x33  17x35 17x34 17x33
  gearbox                                    
1st 29 15 1.93 42.1% 83 85 88 91 96 99 102 102 105 105 108 109 112 112 115 119
2nd 27 19 1.42 57.3% 113 116 120 123 130 134 138 139 142 143 147 148 152 152 157 161
3rd 27 24 1.13 72.4% 143 147 151 156 165 169 174 176 180 181 186 187 192 192 198 204
4th 25 26 0.96 84.7% 167 172 177 182 193 198 204 206 210 211 218 218 224 225 231 238
5th 20 23 0.87 93.7% 185 190 196 202 213 219 226 227 233 234 241 242 248 248 256 264
6th 22 27 0.81 100% 197 203 209 215 227 234 241 243 248 250 257 258 265 265 273 281
                                       

Thanks to Pierre Mazaloubeaux in France once again for providing these helpful charts.

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TZ350 dyno run result.

John Storrie runs a sidecar fitted with a TZ350 engine with his passenger Ian Dagg in the UK based FSRA F350 sidecar championship.

 

 

They recently had the transfer ports opened out by their tuner and the crankcase mouths opened to match.
They also had 1mm machined off the barrel base to alter the port timing.
 

 

John writes:

The red line is the initial run(s) which was with the following settings:

38mm reverse slide carbs
 330 mains, 75 power with 6BFY44 needle in middle slot
 0.0 cutaway with N8 nozzle.
 We run ELF Avgas with 747 at 33:1
 We ran with K&N air filters on each carb

We then went to 310 mains and no air filters, the 330 to 310 change only made about 0.5 BHP so the main change was in the removal of the filters.
We are impressed as the revs show that after 10250 the power is actually dropping and I changed my driving style so that I change up at 10250 and not at 11000.

The power change is amazing, we are actuallly making the front wheel light coming out of hairpins, almost wheelie time.

The tuner did a great job and he is looking into getting barrels made to this pattern as the torque reading is also good, virtually flat from 8000 to 10500 at 35.4 ftlb.

TZ750 Dyno run:

   Click the image left for a look at the printout of Kerry Wilton's recent dyno-run of his TZ750.

Kerry says he just stuck the bike on the dyno, without any tuning at all and is pleasantly surprised with the figures.

TZ750 tips from Russ Bigley:  

To prevent detonation on the 750`s, stock heads are .060" squish and 12 degrees angle.  This should be changed to .050" and 14.5 degrees angle.  YZR heads are offset like a 350G with angle plugs they are .043
squish.  

750 crank cases have too much volume for the size of the intakes carburettors  the bigger the better, Russ recommends  41.3 Lectron HV`s . 

 Picture: Russ Bigley's YZR spec. 750 dyno run

 

TZ750 porting:   Raise the exhaust 1mm and 1mm on each side blend corners to a D shape. Lower intake port floor 2mm.  Open the rear boost ports as wide as possible without endangering the ring endgap. Do not
raise any transfer ports. (Russ Bigley)

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                 TZ 750D/E YAMAHA Porting experiments   by Phil Williams.

Having spent several years in the late 1970`s tuning one of these awesome engines for sidecar use I have often wondered if the modifications I made were infact beneficial or were the results we had just down to a very gifted pilot.

Here I hope to analyse the 750 using some of today’s software and see what happened a bit more accurately than by the seat of the pants, which was all we had back then.    This is how I measure the old cylinder I have, which may or may not be quite   standard.

ENGINE DATA:

 

EXHAUST

Height = 27.5mm     Width = 45mm    Open = 81.7 atdc   Duration = 196.6     

Ta = 9.7085s-sqmm/cc

 

TRANSFER  1

Height = 13mm         Width = 32mm   Open = 114.2 atdc   Duration = 131.6     

 

TRANS 2

Height = 13mm          Width = 12mm    Open = 114.2 atdc    Duration